1 * The destruction of natural environments such as forests and prairies and steppes, whether to create new human settlements or not directly, due to remote human activity, forcing animals to move closer to areas of ancient settlement.

2 * The encroachment of human settlements on wilderness areas.

This encroachment may have several consequences including:

A / the appearance of animals, sometimes parasites or harmful or disease bearers, in the human environment ; and these are the people in precarious situations that are most unable to handle this forced cohabitation and sometimes problematic to the point of containing nuisances.

B / Extinction of species (animal, plant or microbial) either because of:

- The destruction of their natural habitat,

- Or the destruction of their source of food or water,

- Or the occurrence of predators in their environment.

This disappearance is harmful since it breaks a natural balance in favor of other species already harmful or made harmful by their proliferation thus favored exerting a threat to humans, other species, or natural resources, including flora. And yet this extinction may remove species that play a role in the cycle of organic waste generated by the living world.

For decades, the world suffers the fallout from these problems. In addition to the hyper-mediatised and conflictual-issue bird and swine flu, there was:

* The spread of malaria in Africa, which appeared even outside of wetlands etc., because of the heat and humidity in cities ...

* The West Nile virus in the U.S. in the late 90's.

* Cholera in Lima, Peru, that reached Mexico in 1991 and caused a million casualties, knowing that the germ is carried by rats and cockroaches ...

* Chile also known cholera in 90 and 92.

* The Bangladesh during the 90's years, each year with the rainy season, cholera returns, 500 000 cases, 25 000 deaths. The origin was determined as a matter of river water contaminated. 70 000 wells were dug to replace rivers. Another problem was stated, that of arsenic poisoning, that can be due to contamination of ground water by the polluted rivers .

* These are situations where almost always the cities (specifically the slums) have expanded on the expense of forests to house the very poor and ignorant people who are forced to sacrifice hygien expenses and so on, to manage their poor incomes . From there, we can schematize the origin of the half respiratory half hepatic disease observed since mid 2009 in the neighborhood, like this:

- Rats (which occurred in the vicinity of humans accidentally or premeditatedly), carriers of hepatitis and / or scabies (the latter could possibly have a respiratory form).

- Man, poor or indigent, grabs the disease germs (via fleas or contaminated clothes and belongings, or food, or farm animals infected with rats ) and keeps them due to lack of hygien.

- A sick or carrying the infection spreads it to other public places, such as cafes , when using common utensils or things (playing cards, dominoes, cigarettes, narguile or shisha, cups, etc.). Or even when embracing as a welcome, sometimes on the mouth, as for children.

(The issue of child protection in particular, the isolation of infected people and public places in whole, may have been questionable and even harmful, for some; for example, in a spirit of concern, populist or scientific, of immunization by hard life and pathology ordeal ) .